Socket Programming
     What is a socket?
     Using sockets
        Types (Protocols)
        Associated functions
        Styles
        We will look at using sockets in C
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     What is a socket?
     An interface between application and 
       network
        The application creates a socket
        The socket type dictates the style of 
          communication
           • reliable vs. best effort
           • connection-oriented vs. connectionless
     Once configured the application can
        pass data to the socket for network 
          transmission
        receive data from the socket (transmitted 
          through the network by some other host)
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     Socket
     A socket  is an abstract representation of 
       a communication endpoint.
     Sockets  work with Unix I/O services just 
       like files, pipes & FIFOs.
        Treat me as a file, please!
     Sockets (obviously) have special needs:
        establishing a connection
        specifying communication endpoint addresses
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    Unix Descriptor Table
       Descriptor Table     Data structure for file 0
      0
      1
      2                        Data structure for file 1
      3
      4                         Data structure for file 2
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